The present invention relates to oil well downhole tools, and more particularly to an improved oil well dump bailer which is, for example, wireline operable and wherein a movable valve member is mounted within the tool body, the member initially covering a port that communicates with the well bore and, upon triggering of the device, shifts to expose the port so that well bore fluid pressure can enter the tool bore and drive the valve member to its full downward dispensing position.
It is well-known in the oil well drilling and production arts to use cement for various well operations such as, for example, to seal off a certain formation below a production packer so that other producing zones can be perforated. Typically, the dispensing of cement into the well bore is done using a device known in the industry as a "dump bailer." Dump bailers are typically gravity operated, using a very large weight which falls under the force of gravity to dispense any contained cement into the bore. The problem with these types of device is that they often fail to fully dispense the cement product as desired requiring multiple trips and additional expense to the well operation. It is to this problem that the present invention is directed.
The present invention provides an improvement over prior art type dump bailers by providing a dump bailer which uses well bore pressure to move a piston member, (preferably a piston) which fully dispenses the cement product from the well bore. The use of well bore pressure as described herein is an improvement over prior art type dump bailers which rely primarily upon gravity to pull a piston or dispensing member downwardly, or relies upon gravity to pull the cement from the tool body.
Several dump bailers have been patented. For example, U.S. Pat. No. 2,696,258 issued Dec. 7, 1954 to H. M. Green is entitled "Oil Well Cementing Packer." That device discloses a cementing packer wherein a charge is exploded to drive the cement from the bailer. The Green device uses a vertically elongated container with a body of cement contained in the container. A gas generated charge displaces the cement through a lower outlet in the container into the well bore. The device is further characterized by a bore sealing mechanism which is adapted to expand by cement displacing gases to plug the well bore above the zone being cemented, and thus seal the bore against upward dissipation of the force of the gases.
U.S. Pat. No. 2,591,807 issued to H. M. Green on Apr. 8, 1952 and entitled "Oil Well Cementing." The U.S. Pat. No. 2,591,807 discloses an apparatus for depositing cement in a zone within a well bore. The apparatus further includes a vertically elongated container to be lowered into the well bore zone and containing a body of cement, a relatively high velocity explosive charge in the lower portion of the container and serving upon ignition to cavitate the well bore at the zone. A relatively lower velocity explosive charge in the container above the body of cement serves upon ignition to force cement downwardly and outwardly into the cavity and a fuse for igniting the charges extends first to the high velocity charge and then to the lower velocity charge so as to ignite the charges in that order.
U.S. Pat. No. 3,187,813 entitled "Apparatus for Depositing Cement or the Like in a Well" issued June 8, 1965 to H. M. Green, Jr. The U.S. Pat. No. 3,187,813 provides a tool assembly to be lowered into a well on a flexible line and includes a container having a massive cementitious material therein. An opening is provided at the lower portion of the container which can be opened while in the well and thereby allow cementitious material to flow downwardly from the container and into the well by gravity. The assembly is constructed to avoid the application of the cementitious material with any other displacing forces other than gravity during the downward flow so that the cementitious material after leaving the container may seek its own level in the well by gravity.
U.S. Pat. No. 3,208,521 entitled "Recompletion of Well" issued on Sept. 28, 1965 to W. E. Holland et al. The Holland patent discloses a method of forming a plug in a well pipe including the steps of anchoring a support member at a given level in the pipe, depositing a quantity of liquid cementitious mixture on the support member, inserting a conductive metal rod in the cementitious mixture so that the rod extends substantially through the cementitious mixture and is substantially centrally located on the longitudinal axis of the well pipe. After the cementitious mixture has hardened for at least a period of two hours, an electrical direct current is passed from the well pipe to the rod through the hardened cementitious mixture until there has passed at least fifty coulombs of electricity per square inch of contact between the pipe and the cementitious mixture.
A "Method for Cementing Well" issued as U.S. Pat. No. 2,689,008 on Sept. 14, 1954 to T. O. Allen et al. The Allen patent provides a method for cementing a well having a perforated casing therein which comprises locating a body of hydraulic cementitious material in the perforated casing in the region of and adjacent the perforations and locating a high explosive detonating charge in the body of the cementitious material. The charge is discharged and at least a portion of the cementitious material is forced through the perforations thereby dehydrating and setting the portions of cementitious material to seal the perforations.
A "Dump Bailer for Well" issued as U.S. Pat. No. 2,725,940 to G. A. Shidell et al. on Dec. 6, 1955. The Shidell patent discloses a dump bailer for wells including a tubular body, a closure for its upper end including an attachment to a lowering cable, a filler opening in the wall of the body adjacent the closure, a tubular sleeve coaxially connected to the lower end of the body, a removable plug closing lower into the sleeve, and the downwardly facing annular shoulder in the bore of the sleeve axially spaced from the plug, the sleeve having a discharge passage through the wall thereof between the shoulder and the plug, a tubular frangible liner is coaxially positioned in the bore of the sleeve opposite the passage and having one end abutting the shoulder and the other end abutting the plug, an annular resilient seal is disposed to form a fluid type seal between the liner and the wall of the sleeve at points above and below the passage thereby to close off the passage. An electrically fired explosive charge positioned in the bore of the liner is provided and the cable provides a means for firing the charge so as to shatter the liner and open the passage.
U.S. Pat. No. 1,393,311 issued to H. C. Pendelton on Oct. 11, 1921 for a "Method and Means for Facilitating Sealing Deep Wells." The Pendelton device provides a means for facilitating the sealing of a well against water and includes a frangible container adapted to be lowered which is charged with cement into a well and then disrupted, the container having on its leading end a centering device to guide its movement clear of the well, hold surface to prevent premature fracture of the shell.
U.S. Pat. No. 3,379,251 entitled "Dump Bailer" issued on Apr. 23, 1968 to F. O. Bohn. The Bohn patent discloses a dump bailer for depositing material in a well bore. The apparatus includes a reservoir section formed of a length of flexible tubing, a bottom plug closing one end of the reservoir section, a supporting head having a lower portion to which the upper end of the reservoir section is attached, and an upper portion mechanically attaching a wireline cable for positioning the dump bailer in the well bore, and means to fill the reservoir with a material to be deposited. A squeegy is formed of two spaced apart rollers, attached together by crossbars and secured to the upper end of the flexible tubing forming the reservoir section. A pair of pivotally spring loaded fingers are attached to the crossbars for engaging the walls of the bore hole upon any upward movement of the dump bailer so that the squeegy remain stationary and then as the dump bailer is moved upward, the pressure on the bottom of the reservoir is increased ejecting the bottom plug and then positively depositing the material in the reservoir.
An "Apparatus and Method for Completing Wells" issued as U.S. Pat. No. 3,064,733, on Nov. 20, 1962 to H. A. Bourne, Jr. The Bourne patent discloses an attachment for a gun used in perforating wells, comprising a housing attachable to the lower end of the gun, the housing having a cylindrical chamber therein and a plurality of circumferentially spaced outlet ports at the upper end of the chamber. A piston is reciprocally disposed in the chamber, and an energy source in the housing is arranged to raise the piston through the chamber. A hydraulically actuated packer on the housing below the outlet ports is in communication with the chamber and a firing mechanism for the gun in the housing is arranged to be actuated by the piston as the piston reaches the upper end of the chamber.
U.S. Pat. No. 3,318,393 entitled "Formation Treatment" issued May 9, 1967 to T. D. Brown. The Brown patent describes a wireline apparatus for treating a permeable earth formation zone containing a formation fluid under pressure and traversed by a case bore hole containing a column of fluid extending upwardly of the zone providing a hydrostatic pressure environment within the casing greater than the pressure of formation fluid. The apparatus includes a body adapted to be lowered within the bore hole by means of a wireline, a perforator including explosive material disposed on the body for perforating the casing along a predetermined axis to establish fluid communication with the formation therebeyond when the explosive material is fired, a compartment in the body providing a volume of low pressure gas of a size to contain any gases evolving from the explosive material when fired at a pressure less than the pressure of the formation fluid, a sealing mechanism on the body for isolating the fluid communication from the hydrostatic pressure environment of the bore hole by sealing off an isolated area of the casing wall when urged thereagainst .